The present invention pertains to a method and a device for creating a hinge-like bendable zone in a sheet of paper, paperboard, cardboard or foil, particularly a brochure cover, by means of rotatively driven tools.
Methods in which material is compressed and/or displaced are conventionally employed for creating hinge-like bending zones or lines in a sheet of paper, paperboard, cardboard or foil, especially for use in covers for books or brochures (collectively, “cover sheets”). In this case, the sheet is scored along the bending line such that the bending resistance in the bending line is reduced and the stability of the sheet is barely changed.
Various scoring devices with rotatively driven tools are listed on page 116 of the technical book “Industrial Bookbinding” by Dieter Liebau and Inès Heinze, Publishing House Beruf+Schule, 2001. An upper tool in the form of a scoring blade or a scoring disk carries out the scoring process in cooperation with a lower tool that may consist of a sleeve with a circumferential radial groove or be composed of two opposite sleeves with rounded edges, the gap between which is adjustable. It is also known to utilize a scoring blade for directly scoring against a cylindrical rubber roller.
In order to realize the scoring with adequate quality such that a uniform scoring bead is produced and no tearing of the upper and lower sides occurs, the geometric relations (width of the scoring blade, width of the groove in the lower tool and depth of penetration of the scoring blade) need to be adapted to the respective material to be scored. It may even be required to exchange the tools if the product thickness varies significantly.
DE 200 22 488 U1 describes a scoring device in which the scoring blade consists of an elastic ring that is exchangeably accommodated in a groove of the upper tool. The upper tool features several grooves of different widths and depths that are arranged adjacent to one another such that rings of different diameters and/or geometries can be inserted into the upper tool. In addition, the lower tool features a series of adjacently arranged grooves that can be allocated to the respective rings of the upper tool with respect to the material to be scored and the material thickness by means of a color code. In this case, it is disadvantageous that rings need to be exchanged and that the upper and lower tools need to be positioned relative to one another anew in accordance with a predetermined allocation matrix if the material or the material thickness changes, wherein these procedures require a significant set-up effort.